Support arm



FIG. 1 is a perspective view of a support arm showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is a perspective view of the support arm shown in an alternate configuration; and,

FIG. 9 is another perspective view of the support arm shown in an alternate configuration.

The evenly dashed broken lines depict portions of the support arm that form no part of the claimed design. 

CLAIM The ornamental design for a support arm, as shown and described. 